The present invention relates to portable radio equipment having a display and, more particularly, to the structure of a loop antenna installed in such portable radio equipment which prevents the gain of the antenna from being lowered despite the fact that a conductive support member or frame, which fixes a display in place, is located in close proximity to the antenna.
A modern paging receiver or similar radio equipment having a display has various advanced functions and has a miniature handy configuration. The miniature design of this kind of equipment is accomplished by arranging various elements of the equipment close to each other in a dense configuration on a printed circuit board, For example, a loop antenna and a support frame for fixing an LCD (Liquid Crystal Display) or similar display element are usually positioned in close proximity and in parallel with each other. In general, a higher antenna gain is achievable by: allowing an antenna to occupy as large an area as possible on a printed circuit board. Stated another way, a decrease in the area which an antenna occupies on a printed circuit board invites an increase in loss resistance and thereby a decrease in antenna gain. On the other hand, the support frame is generally made of stainless steel, phosphor bronze or similar conductive metal. Hence, when the support frame and loop antenna are positioned close to each other, a current opposite in direction to a radiation current which flows through the antenna is induced in the support frame to cancel the radiation current. This lowers the antenna gain and thereby the sensitivity of the radio equipment. Therefore, when the metal frame is positioned in the vicinity of and in parallel with the antenna, there has to be provided some implementation for preventing the antenna gain from being lowered. The decrease in antenna gain would be more aggravated if other structural elements having influence on the antenna were also located close to the antenna.